Cell proliferation and ploidy of human solid tumours: Methodological experience with in vivo bromodeoxyuridine and DNA flow cytometry

A sequential procedure for single and multiparameter flow cytometry (FCM) that allows detailed cell proliferation and DNA ploidy studies of human solid tumours is reported here. This description includes time collection and storage, tissue disaggregation and staining as well as FCM analysis of samples. The overall feasibility, together with some critical aspects of the DNA/bromodeoxyuridine (BrdU) in vivo assay for cell kinetic studies in human solid tumours, are reported, based on our experience in recent years. We found that the BrdU in vivo method, coupled with bivariate FCM for measurements, is a valuable approach for a 'dynamic' assessment of tumour cell proliferation in the clinical setting. Routine measurements can be achieved providing that well standardised tissue disaggregation and immunolabelling procedures are performed. In different solid tumours, cytokinetic results were satisfactory in 85% of cases as far as the BrdU-labelling index is concerned while 70% were acceptable for DNA synthesis time and tumour potential doubling time. Causes of failure are also considered and discussed. In order to guarantee the finest detection of aneuploidy, routine high resolution single-parameter DNA analysis is suggested. Our experience with further improvements in cell kinetic studies based on the possibility of gating the BrdU/DNA analysis for a subpopulation of interest (i.e. cytokeratin-positive cells in epithelial tumours) is also reported.